|Pre planting phase|
|Early vegetative phase|
|Late vegetative phase|
|Post productive phase|
Land preparation typically involves plowing, harrowing, and leveling the field to make it suitable for crop establishment. Draft animals, such as buffalo and oxen, 2-wheel tractors or 4-wheel tractors can all be used as power sources in land preparation. The initial soil tillage can also be performed with a rotovator instead of a plow.
The vast majority of Asian rice fields are first flooded with water before tillage. This tillage of flooded soil is referred to as puddling. Soil flooding and soaking is performed once and requires sufficient water to bring the topsoil to saturation and create an overlying water layer. Soil puddling destroys soil structure, which reduces percolation rates and loss of water. It also results in high resistance to root penetration, low porosity, and permeability and in the formation of a soil plow pan; all of which can restrict root growth.
Puddling is very efficient in clay soils that form deep cracks penetrating the plow pan at about 15 to 20 cm soil depth during the period of soil drying before land preparation. Although puddling reduces percolation rates of the soil, the action of puddling itself consumes water. There is a trade-off between the amount of water used for puddling and the amount of water “saved” during the crop growth period as a result of reduced percolation rates. Puddling is less effective in coarse soils, which do not have enough fine clay particles to migrate downward and fill up the cracks and pores in the plow pan.
A well-leveled field is a prerequisite for good water and crop management. When field are not level, water may stagnate in the depressions whereas higher parts may fall dry. This results in uneven crop emergence and uneven early growth, uneven fertilizer distribution, and possibly additional weeds. Effective land leveling will :
Land preparation for dry seeding typically involves consists of plowing or rotovating followed by harrowing and leveling of dry and friable soil. The crop is established by broadcasting or drilling seed that has not been pre germinated.
Farmers can reduce water use by shifting from puddled to non-puddled land preparation. Large amounts of water (20–40% of total water use) are consumed during land preparation of flooded soils because of the need to initially soak dry and cracked soil, and to keep the field continuously flooded. Most of the wasted water is lost by drainage through soil cracks. Dry land preparation does not require irrigation water because it can be done when the soil has the correct water contact and is friable for plowing or rotovating and harrowing.
|< Prev||Next >|